I'm working on JBoss AS 7 using JPA to have a List of Beans in a Entity-Bean like this:
#Entity
class section {
#Id
#GeneratedValue
private Long id;
#ManyToOne
private List<Component> components;
// ...
The table to join the two tables gets created, but it does not contain an Id, which leads to JPA creating a unique-constrain on one of the columns (SECTION_ID). Which is not really what I want, because one section can have more than one component. One component can be used in more than one section too.
I already tried
#JoinTable(name="SECTION_COMPONENT",
joinColumns = {
#JoinColumn(name="section_id", unique = false)
},
inverseJoinColumns =
#JoinColumn(name="component", unique = false)
}
I guess JPA needs at least one unique column, so it just adds that to the last column if nothing else is specified. I'd be fine with adding a new column "id" to set up a primary (or unique) key. But I am not sure how to do that.
Thanks a lot for any help
The mapping is not correct: #ManyToOne in your case means that you have one component that has many sections:
#ManyToOne
private Component component;
According to your description, you need an #ManyToMany relationship:
#ManyToMany
private List<Component> components;
Related
I created an entity/table for a book, and I want to achieve that each element can reference another book to create a series.
I came up with this:
#Entity
public class Book {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Integer bookId;
#Lob
private String text;
#OneToOne
#JoinColumn(name = "book_id")
private Book previousPart;
}
However, the attribute previousPart is not seen as a column in my Database, while the others are. Is there a different annotation I have to use or is this the wrong way to model a relationship like this? Or do I have to use the type Integer instead of Book directly (I thought this was what the framework does internally)?
Try this way:
#OneToOne
#JoinColumn
private Book previousPart;
In your code you defined the book_id field as the join-column, which is an already existing column (the id itself), so actually you linked all entries to themselves.
I'm trying to use Map in Spring Data JPA to handle the relationship to store records of equipment quantity.
I followed this guide to create the entity.
Meeting{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "meeting_id", updatable = false)
#JsonIgnore
private int id;
#ElementCollection
#MapKeyColumn(name = "equipment_type")
#MapKeyEnumerated(EnumType.STRING)
private Map<EquipmentType, Integer> equipment = new HashMap<>();
}
EquipmentType is an Enum.
This is the table for the property:
CREATE TABLE IF NOT EXISTS meeting_equipment (
meeting_id INTEGER NOT NULL REFERENCES meeting (meeting_id),
equipment_type VARCHAR(10) NOT NULL,
quantity INTEGER NOT NULL DEFAULT 0
);
Once I try to create a meeting entity, I get error ERROR:column "meeting_meeting_id" of relation "meeting_equipment" does not exist
May I know what's the problem here?
Your table meeting_equipment does not match what JPA is expecting.
It has a column meeting_id but your JPA implementation expects meeting_meeting_id
Either rename the column to the expected meeting_meeting_id or configure your mapping to use the current column name. I think this might do the trick:
#JoinTable(joinColumns={#JoinColumn(name="meeting_id")}
Of course, you probably can create your own naming strategy if you have many cases like this and want to keep your column names as they are.
I'm new to Stackoverflow, so I will make my best to conforms with usage. I was wondering if there were a way to get a complete list of changes/snapshots of a given Entity. For now it works well with edition of Singular Properties, as well as Addition and Deletion to Collection Property. But I'm unable to find when a Child Entity in the Collection Property was updated.
Given two Entities, and a LinkEntity:
#Entity
class Person {
#Id
Long id;
#OneToMany(mappedBy = "person", cascade = CascadeType.ALL)
Set<LinkAddress> addresses;
}
#Entity
class Address {
#Id
Long id;
#OneToMany(mappedBy = "address")
Set<Address> persons;
}
#Entity
class LinkPersonAddress {
#Id
Long id;
#ManyToOne
#ShallowReference
Person person;
#ManyToOne
#ShallowReference
Address address;
String linkType;
}
My use case is following. I get a specific Person by Id #1, and then mutate the type of specific Address (ie. HOME --> WORK). I save the Person back with the modified Set and let JPA Cascade my changes. Although all Spring Data Repositories for Person, Address, and LinkPersonAddress are annotated with #JaversSpringDataAuditable, I cannot retrieve this "update" using Javers QueryBuilder with the class Person and Id #1. It makes sense as I should query the class LinkPersonAddress instead, but how can I specify that I want only the changes from LinkPersonAddress relevant to Person with Id #1.
PS: Please apologize any typos in code snippets, as I didn't write it in my Dev Environment.
Let's start from the mapping. You did it wrong, Address is a classical ValueObject (see https://javers.org/documentation/domain-configuration/#value-object) not Entity. Because:
Address doesn't have its own identity (primary key genereted by a db sequence doesn't count)
Address is owned by the Person Entity. Person with its Addresses forms the Aggregate.
When you correct the mapping, you can use ChildValueObjects filter, see https://javers.org/documentation/jql-examples/#child-value-objects-filter
I have two indexed entities.
Player:
#Indexed
#Entity
public class Player {
#Field
private String firstName;
#ContainedIn
#ManyToOne
private Club playersClub;
}
and Club:
#Indexed
#Entity
public class Club {
#Fields({
#Field(store=Store.COMPRESS),
#Field(name = "sorting_name", analyze = Analyze.NO)
})
private String name;
#IndexedEmbedded(depth = 1)
#OneToMany(mappedBy = "playersClub")
private Set<Player> players;
}
Now when I search into ClubSearchService like this:
luceneQuery = queryBuilder
...
.onField("name").andField("players.firstName")
...
it works fine, but when I want search in other way(PlayerSearchService):
.onField("firstName").andField("lastName").andField("number").andField("country").andField("playersClub.name")
there is an error
org.hibernate.search.SearchException: Unable to find field playersClub.name in pl.domain.Player
Hibernate Search cannot search into ManyToOne item?
Yes it is possible to index ManyToOne relations as well.
In most simple cases you have one entity such as Club marked as #Indexed and then you want to index some of its fields and also embed via #IndexedEmbedded attributes from a related entity Player.
So far you got it right, and this is defining essentially the "flattened" schema for your club index.
The problem is that when defining the schema for the player index you marked firstname as an indexed field, but didn't instruct it to embed the relation to playersClub. Essentially you're missing the #IndexedEmbedded on this property.
To not be confused with the #ContainedIn annotation: this is purely to make sure that Hibernate Search will re-index the entities in which it is contained; it is not making both sides embedding each other in a symmetric way.
In more formal terms, the relation established by #IndexedEmbedded is a directed graph: if you want it to follow both directions you have to establish them both explicitly.
I have an entity class that is simply a ManyToMany with extra column, as follows:
#Entity
#Table(name = "view_templates_device_types")
public class ViewTemplateDeviceTypeEntity implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#ManyToOne
#JoinColumn(name = "view_template_id")
private ViewTemplateEntity viewTemplate;
#Id
#ManyToOne
#JoinColumn(name = "device_type_id")
private DeviceTypeEntity deviceType;
#Column(name = "priority", nullable = false)
private int priority;
public ViewTemplateDeviceTypeEntity() {
}
...
}
I noticed that when I create a new object of this type, set viewTemplate and deviceType to values that have corresponding data in the db and I call entityManager.persist(entity) the data is stored. But when I call entityManager.merge(entity) instead of persist I get an exception:
SQL Error: 1048, SQLState: 23000
Column 'view_template_id' cannot be null
I thought that calling merge should result with data inserted into database in case it is not stored yet. It is quite important to me to use merge here (because of cascades). What can I do to make it work?
As per the JPA spec, section 2.4
"A composite primary key must correspond to either a single persistent field or property or to a set of such fields or properties as described below. A primary key class must be defined to represent a composite primary key. Composite primary keys typically arise when mapping from legacy databases when the database key is comprised of several columns. The EmbeddedId or IdClass annotation is used to denote a composite primary key. See Sections 11.1.17 and 11.1.22.".
So you either need #IdClass or #EmbeddedId. Anything else is non-portable and prone to error. I am very surprised of any JPA provider that does not throw out warnings for this.